Reports are rife that the Argentina star has handed in a transfer request as he wants to be playing regular first-team football, but Valverde is keen for him to stay.
Speaking ahead of the clash against Sporting in the Champions League, Valverde played down his transfer plans and insisted Mascherano remained an important member of the Barcelona squad.
"The transfer window hasn't arrived yet. We've been talking about the winter transfer window since August," he said. "When it comes we will talk about the winter transfer window. We are still counting on Mascherano. He is a member of the team, is committed to Barcelona and has been for a long, long time.
"I can't talk about hypothetical conversations really. I'm happy with Mascherano. I want him to be here with us. I've not got concern about him."